This invention relates to a system and method for controlling the mass flow rate of a blower which is driven by an electronically commutated motor (ECM).
The accurate regulation of mass flow rate of a blower (more precisely the mass flow rate of the gaseous medium transported through the blower) is required in numerous commercial and non-commercial contexts. For example, in a zoned forced air heating system for use in residences, it is advantageous to maintain a desired supply air flow under varying resistances of the heating system, which occur e.g. when heating zones are opened and closed. It is obvious that a regulation of the mass flow would be possible by direct measurement of the actual mass flow rate in a closed-loop control system. However, such measurement requires quite complicated and expensive measuring devices, and it is difficult to obtain in a cost-effective manner precise and fast results that could be used as feedback signals in an electronic control loop.
Accordingly, it is an object of the invention to provide a system and method for accurate, inexpensive mass flow control of a blower without a direct measurement of the actual mass flow rate or the blower pressure rise. The desired mass flow rate should be maintained under varying resistances of the system to which the gaseous medium is supplied by the blower. Furthermore, regulation over a wide range of mass flows should be possible.